APL-based flexibility analysis of manufacturing grid

With the characteristics of diversity, randomness, concurrency and decomposability, tasks in manufacturing field are very complicated, and so manufacturing grid(MG)should have considerable flexibility to deal with this problem. With the definition of node and arc, MG structure is converted into a small-world network. Given construction cost constraint, the problem of shortest task waiting time is transformed into the constrained optimization problem, and a corresponding flexibility analysis model based on average path length(APL)is proposed, and the premise of arc-length and node-distance are defined. The results of application example show that the analysis model is effective.     

无线传感器网络中基于网格的能量感知路由协议研究(英文)

通过建立无线传感器网络环境中的能耗模型, 研究了高效能耗以及由路径损耗模型不同带来的数据干扰问题. 采用二维网格分簇机制, 其中簇头选举算法基于节点的剩余能量和随机退避时间, 以一种高效且分散的方式使簇头在所有传感器节点中均匀轮换. 节点除了在传输和接收数据过程中消耗能量, 在干扰重传时也需要消耗额外的能量. 根据平面几何学, 通过分析和数学推导, 得出网络的总能耗与分簇机制中的网格结构直接相关的结论, 其中簇的大小决定传输范围, 节点距离决定路径损耗指数, 网络结构决定同时传输数据的节点产生的干扰总数. 通过分析和仿真实验, 提出了在无线传感器网络中优化的网格结构和对应的网格大小, 从而在最大化降低能耗和最小化总体冲突之间达成平衡.     

基于事件的网格计算协作模式

面向模式的软件体系结构已成为软件工程的一个热点,而网格计算也正在成为下一代互联网的发展趋势,基于网格计算的模式研究成为模式研究的一个重要发展方向。文中分析了现有的几种网格计算模式的应用范围,详细介绍了基于事件的协作模式网格计算算法结构设计模式。     

网格环境下的图书馆数字化发展研究

t随着网络的广泛应用,图书馆早已进入网络化管理时代。以电子文档及多媒体格式存储的大量文献为人们的学习和科研提供了极大的方便。但由于网络技术所存在的局限性及电子资源所具有的商业性,决定了现有各种电子文献资源依然存在着“信息孤岛”和重复建设的现象。网格时代的到来将对图书馆的数字化建设带来一场新的技术革命。     

网格技术：图书馆工作变革的催化剂

网格技术是近年来兴起的一种重要信息技术,具有高效性、集成性、共享性等功能特点。从五个方面论述了网格技术将给图书馆工作带来的新变化,最后讨论了图书馆应用网格技术需要解决的问题。     

On maximum power point tracking control strategy for variable speed constant frequency wind power generation

Based on the characteristic of AC-excited variable speed constant frequency （VSCF） wind power generation, the vector control technique was applied in a doubly fed induction generator （DFIG）. Maximum wind energy or maximum output power point can be tracked by decoupling control of active power and reactive power. The research result shows that the net power of generation system delivered to grid in maximum wind energy tracking mode is not the most. We presented a novel maximum power point tracking （MPPT） control strategy by analyzing the DFIG mathematic model and power relations which delivered the maximum power to the grid. The maximum power point could be tracked automatically without measuring wind speed in the control strategy and the control was independent of optimal turbine power curve, which had excellent dynamic and static performances and robustness. Simulation and experimental results testify the accuracy and validity of the control strategy.     

基于网格的并行数据挖掘算法的实现

随着信息技术的发展,大量的数据不断被收集和存储,对数据的挖掘规模越来越大,传统的数据挖掘已经无法解决海量数据挖掘问题。网格技术的发展,使得广域分布的海量数据的挖掘问题得到解决。文章根据现实中海量数据挖掘的需求和网格的本质,把并行关联规则挖掘算法应用于网格数据挖掘中,并建立了一个并行数据挖掘模型,验证了并行数据挖掘系统在网格环境的可行性与合理性。     

网格市场中服务质量驱动下的任务调度算法

针对资源提供方不能完成用户所有任务的情况,提出一种服务质量驱动下的任务调度算法,即预算和截止时间限制下的最大任务完成数调度算法(DBCN).这种批调度算法结合了Min-min算法吞吐量较高和线性规划全局优化的优点,不仅考虑了用户的所有任务,同时还考虑了优先级较高的任务.实验结果表明,该算法在任务完成总数方面比经典算法Min-min和DBCT分别提高了约10.6%和22.0%,在优先级高的任务完成总数方面也有大幅度提高,分别约为20%和40%.     

Swedish PE teachers struggle with assessment in a criterion-referenced grading system

In the field of education, the international trend is to turn to criterion-referenced grading in the hope of achieving accountable and consistent grades. Despite a national criterion-referenced grading system emphasising knowledge as the only base for grading, Swedish physical education (PE) grades have been shown to value non-knowledge factors, such as students’ characteristics and behaviour. In 2011, a new national curriculum was implemented which attempts to deal with the problem by prescribing specific knowledge requirements with a clear progression as the only basis for different grades. The aim of the present study is to explore the impact of the new knowledge requirements on what teachers consider important when assigning grades. It is also to discuss what non-knowledge-related aspects (if any) teachers continue to look for and why these seem to remain resilient to the reform. The Repertory Grid technique was employed to interview the teachers before (2009) and after the implementation (2013). During the interviews, the grading of 45 students was discussed, which generated 125 constructs. After the implementation, there was a near doubling of knowledge constructs, half as many motivation constructs and an almost total elimination of constructs based on confidence and social skills. While motivational factors were still considered valuable for the award of a higher grade, clear criteria seemed to be important, but too limited for the teachers’ needs. In order to understand the persistence of motivational factors, we discuss the results in relation to Bernstein’s interrelated message systems of curriculum, pedagogy and assessment. We emphasise the need to discuss how valid grades can be achieved and, at the same time, give value to the regulative discourse in order to realise the overarching national goals of values and norms in education and PE.     

电网项目海外投资案例研究与风险识别

在分析电网项目海外投资现状的基础上,以两个典型的电网海外投资项目为例,分析和梳理在投资过程中潜在风险因素,并结合现有相关文献,构建电网项目海外投资风险指标体系。在此基础上面向电网海外投资专家和相关研究人员,针对风险的发生可能性、造成损失水平和可控制性等三方面进行问卷调查及统计分析工作,风险水平的计算引入脆弱性理论,进而明确各风险因素的重要性排序,为电网项目海外投资过程中的风险管理提供一定的参考意义。